Synchronism in radio movies



Feb. 28, 1928. 1,660,711

C.F'. JENKINS sYNcHRonISm IN RADIO uovIEs Filed llay 21, 1927 /A EN E E AMP Patented Feb. 2s, 192s.

CHARLES FnANrs JENKINS, or WASHINGTON, DISTRICT or COLUMBIA.

SYNCHRONISM vIlil' RADIO MOVIES.

Application led Hay 21,

This invention relates to methods of synchronizing distant1y-separated motors, with particular reference to the motors driving mechanisms used in thetransmission and reception of radio vision and television.

Heretofore the nmethod most frequently employed in the control of the speed ofthe several motors has been by the beat of tuning forks. Another method is the direct coupling of the transmitting and receiving motors to the same source of power with synchronous motors either directly or with ampliied synchronous impulses. But when great distances separate the receivers from the transmitter neither of these methods are t acceptable for radio movies and radio vision.

The herein-described method consists in maintaining synchronism by the symmetry of the picture itself, or re-attaining it by the asymmetry of the picture.

In the drawings Fig. 1 is a front view of the screen upon which the radio movies are projected; Fig. 2 an edge-view of the screen, and a schematic drawing of the mechanism for automatically attaining synchronism, and for shiftin the picture. on the screen; Fig. 3 mechanism for manually attaining `s nchronism; and Fig. 4 another view of the picture screen, in reduced scale.

In the several iigures, A is a picture screen; B a light-sensitive cell; C an ampliiier'l connected thereto; D the electromagnet of a relay; E the armature of this relay; F a contract on the armature; G a motor; H a rheostat in one of the circuits of the motor (the armature circuit, in the hereinafter description) d a spiral gear driven by the gear Kv on the shaft of the motor, and L a hand Wheel for shifting the motor gear along the squared shaft of the motor. M is a source of current for the motorf, and N a frame line between the upper half of one picture frame and the lower half of the adjacent picture frame in the picture being projected on the screen.

This invention relates only to the synchronous control of the motors, which may be the motors used in radio movies and radio vision and as the scanning mechanism is no part of the invention, it is not here illustrated-any scanning mechanism will answer.

When a motion picture first appears on the screen it is not usual to nd it ramed; it is more likely to be out of frame with a 1927. Serial N0. 193,259.

frame line appearing across the screen (as at N' 1n Fig. 4), straight or askew. The framing of the picture is then attained by shifting the rotative relation of the receiving mechanism with respect to the rotation of the transmitting mechanism ;-not by a change of speed `of the motors, but the rotative relation of the motors. I

This framing of the picture, i. e., the shifting of the rotative relation of the receiver and transmitter is attained by sliding the spiral gear K along the square shaft of the motor G. Such shifting of this gear either advances or retards the gear J which driyes the scanning mechanism, and is done while it continues in motion. The framing of the picture is completed, of course, when the frame line N disappears at the top or bottom of the picture screen.

Synchronism of the motor of the receiver mechanism and the transmitting machine to square up or rectify the picture from a picture which is askew as suggested by dotted lines in Fig. 1, is attained by speeding or slowing the motor of the receiver until the picture on the screen is squared, that is, until the screen shows an acceptable'picture.

This changing of the motor speed results from the rotation of the hand Wheel of rheostat H, Fig. 4, to increase or decrease the resistance of the motor circuit.

In Fig. 2 mechanism is provided for automatically bringing the receiver motor into synchronism with the transmitter motor. In the corner of the picture screen an oblong aperture A2 is cut. Behind this opening a light-sensitive cell is located. When a picture is projected askew on the screen( as shown by dotted lines, Fig.1),no light passes through the aperture, and the relay contact at F is closed and the rheostat H short-circuited, speeding up the motor until the picture is squared up on the screen. When this hapn pens light passes through the aperture, activates the Cell and opens the relay Contact at F. This puts the resistance H into the motor circuit and the mot-or slows down. It has been found rather easy to so adjust the rheostat H that the motor will run in exact synchronism with the transmitter motor. s

What I claim isi. In a deviceof the character described, the combination of a screen and a receiver motor, a light sensitive cell adjacent said screen energizable when a picture is projectedt en the screen in uu unitrumect pceiticn, und means for electrically cenneetnie,w eriici ceti cnet meter whereby upon energizntien cit" the ceti the motor circuit ie changed te reduce the spacci et the motor.

2. tin e (ier/ice et the character ciescriheci,

the combination cit c, motor, e resistance ucr meiiy ehertmircuitedt with' respect tu eeidi meter, c remy having c ccntect in circuit with the motor endl normally operative te ehort circuit said resistance, e iight sensitive celi in circuit with Seidl meter., enti menne operable by energizeticn cet seidceii te @pen Seid rehiy sind piece the resistance in the meter circuit te reduce the epeedl uit the meter.

3., Tin e riet/ice cui' the cherecter cleecrihedl incurrir having receiver en transmitting motors en scanning mechanism., the comhination et ineens rer eutomaticeiy changing the meter phcses te synchronize the seme, endl manuel menus tor changing the eai phase compris-:ing e, spiral gear slidable en one of the meter ehcitts, e second geir adapted te operete the scanning mechanism meshing with seid spire] geen'7 and means engaging eeict spiral geer and operable te siide the seme en the shaft', thereby edvancing or retarding the seid second. gear tc shift the retetive reteticnferl the meter.

iin testimony whereof have exe my signature.,

erinnere renners crimine., 

